Try to make silent_mode behave somewhat reasonably.

Instead of sending stdout/stderr to /dev/null after forking away from the
terminal, send them to postmaster.log within the data directory.  Since
this opens the door to indefinite logfile bloat, recommend even more
strongly that log output be redirected when using silent_mode.

Move the postmaster's initial calls of load_hba() and load_ident() down
to after we have started the log collector, if we are going to.  This
is so that errors reported by them will appear in the "usual" place.

Reclassify silent_mode as a LOGGING_WHERE, not LOGGING_WHEN, parameter,
since it's got absolutely nothing to do with the latter category.

In passing, fix some obsolete references to -S ... this option hasn't
had that switch letter for a long time.

Back-patch to 8.4, since as of 8.4 load_hba() and load_ident() are more
picky (and thus more likely to fail) than they used to be.  This entire
change was driven by a complaint about those errors disappearing into
the bit bucket.

Author: tglsfdc

doc/src/sgml/config.sgml

@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.223 2009/08/04 16:08:35 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.224 2009/08/24 20:08:31 tgl Exp $ -->
 
 <chapter Id="runtime-config">
   <title>Server Configuration</title>
@@ -2588,7 +2588,37 @@ local0.*    /var/log/postgresql
         </para>
        </listitem>
       </varlistentry>
-      
+
+     <varlistentry id="guc-silent-mode" xreflabel="silent_mode">
+      <term><varname>silent_mode</varname> (<type>boolean</type>)</term>
+      <indexterm>
+       <primary><varname>silent_mode</> configuration parameter</primary>
+      </indexterm>
+      <listitem>
+       <para>
+        Runs the server silently. If this parameter is set, the server
+        will automatically run in background and disassociate from the
+        controlling terminal.
+        This parameter can only be set at server start.
+       </para>
+
+       <caution>
+       <para>
+        When this parameter is set,
+        the server's standard output and standard error are redirected
+        to the file <filename>postmaster.log</> within the data directory.
+        There is no provision for rotating this file, so it will grow
+        indefinitely unless server log output is redirected elsewhere
+        by other settings.  It is recommended that <varname>log_destination</>
+        be set to <literal>syslog</> or that <varname>logging_collector</> be
+        enabled when using this option.  Even with those measures, errors
+        reported early during startup may appear in
+        <filename>postmaster.log</> rather than the normal log destination.
+       </para>
+       </caution>
+      </listitem>
+     </varlistentry>
+
       </variablelist>
     </sect2>
      <sect2 id="runtime-config-logging-when">
@@ -2722,26 +2752,6 @@ local0.*    /var/log/postgresql
        </listitem>
       </varlistentry>
 
-     <varlistentry id="guc-silent-mode" xreflabel="silent_mode">
-      <term><varname>silent_mode</varname> (<type>boolean</type>)</term>
-      <indexterm>
-       <primary><varname>silent_mode</> configuration parameter</primary>
-      </indexterm>
-      <listitem>
-       <para>
-        Runs the server silently. If this parameter is set, the server
-        will automatically run in background and any controlling
-        terminals are disassociated.
-        The server's standard output and standard error are redirected
-        to <literal>/dev/null</>, so any messages sent to them will be lost.
-        Unless <application>syslog</> logging is selected or
-        <varname>logging_collector</> is enabled, using this parameter
-        is discouraged because it makes it impossible to see error messages.
-        This parameter can only be set at server start.
-       </para>
-      </listitem>
-     </varlistentry>
-
      </variablelist>
 
     <para>

src/backend/postmaster/postmaster.c

@@ -37,7 +37,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.589 2009/08/24 18:09:37 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.590 2009/08/24 20:08:32 tgl Exp $
  *
  * NOTES
  *
@@ -191,7 +191,7 @@ static int	SendStop = false;
 
 /* still more option variables */
 bool		EnableSSL = false;
-bool		SilentMode = false; /* silent mode (-S) */
+bool		SilentMode = false; /* silent_mode */
 
 int			PreAuthDelay = 0;
 int			AuthenticationTimeout = 60;
@@ -744,7 +744,7 @@ PostmasterMain(int argc, char *argv[])
 	}
 
 	/*
-	 * Fork away from controlling terminal, if -S specified.
+	 * Fork away from controlling terminal, if silent_mode specified.
 	 *
 	 * Must do this before we grab any interlock files, else the interlocks
 	 * will show the wrong PID.
@@ -894,20 +894,6 @@ PostmasterMain(int argc, char *argv[])
 	 */
 	set_max_safe_fds();
 
-	/*
-	 * Load configuration files for client authentication.
-	 */
-	if (!load_hba())
-	{
-		/*
-		 * It makes no sense continue if we fail to load the HBA file, since
-		 * there is no way to connect to the database in this case.
-		 */
-		ereport(FATAL,
-				(errmsg("could not load pg_hba.conf")));
-	}
-	load_ident();
-
 	/*
 	 * Initialize the list of active backends.
 	 */
@@ -1023,6 +1009,20 @@ PostmasterMain(int argc, char *argv[])
 	 */
 	autovac_init();
 
+	/*
+	 * Load configuration files for client authentication.
+	 */
+	if (!load_hba())
+	{
+		/*
+		 * It makes no sense to continue if we fail to load the HBA file,
+		 * since there is no way to connect to the database in this case.
+		 */
+		ereport(FATAL,
+				(errmsg("could not load pg_hba.conf")));
+	}
+	load_ident();
+
 	/*
 	 * Remember postmaster startup time
 	 */
@@ -1204,15 +1204,46 @@ reg_reply(DNSServiceRegistrationReplyErrorType errorCode, void *context)
 
 
 /*
- * Fork away from the controlling terminal (-S option)
+ * Fork away from the controlling terminal (silent_mode option)
+ *
+ * Since this requires disconnecting from stdin/stdout/stderr (in case they're
+ * linked to the terminal), we re-point stdin to /dev/null and stdout/stderr
+ * to "postmaster.log" in the data directory, where we're already chdir'd.
  */
 static void
 pmdaemonize(void)
 {
 #ifndef WIN32
-	int			i;
+	const char *pmlogname = "postmaster.log";
+	int			dvnull;
+	int			pmlog;
 	pid_t		pid;
+	int			res;
+
+	/*
+	 * Make sure we can open the files we're going to redirect to.  If this
+	 * fails, we want to complain before disconnecting.  Mention the full path
+	 * of the logfile in the error message, even though we address it by
+	 * relative path.
+	 */
+	dvnull = open(DEVNULL, O_RDONLY, 0);
+	if (dvnull < 0)
+	{
+		write_stderr("%s: could not open file \"%s\": %s\n",
+					 progname, DEVNULL, strerror(errno));
+		ExitPostmaster(1);
+	}
+	pmlog = open(pmlogname, O_CREAT | O_WRONLY | O_APPEND, 0600);
+	if (pmlog < 0)
+	{
+		write_stderr("%s: could not open log file \"%s/%s\": %s\n",
+					 progname, DataDir, pmlogname, strerror(errno));
+		ExitPostmaster(1);
+	}
 
+	/*
+	 * Okay to fork.
+	 */
 	pid = fork_process();
 	if (pid == (pid_t) -1)
 	{
@@ -1231,8 +1262,8 @@ pmdaemonize(void)
 	MyStartTime = time(NULL);
 
 	/*
-	 * GH: If there's no setsid(), we hopefully don't need silent mode. Until
-	 * there's a better solution.
+	 * Some systems use setsid() to dissociate from the TTY's process group,
+	 * while on others it depends on stdin/stdout/stderr.  Do both if possible.
 	 */
 #ifdef HAVE_SETSID
 	if (setsid() < 0)
@@ -1242,14 +1273,26 @@ pmdaemonize(void)
 		ExitPostmaster(1);
 	}
 #endif
-	i = open(DEVNULL, O_RDWR, 0);
-	dup2(i, 0);
-	dup2(i, 1);
-	dup2(i, 2);
-	close(i);
+
+	/*
+	 * Reassociate stdin/stdout/stderr.  fork_process() cleared any pending
+	 * output, so this should be safe.  The only plausible error is EINTR,
+	 * which just means we should retry.
+	 */
+	do {
+		res = dup2(dvnull, 0);
+	} while (res < 0 && errno == EINTR);
+	close(dvnull);
+	do {
+		res = dup2(pmlog, 1);
+	} while (res < 0 && errno == EINTR);
+	do {
+		res = dup2(pmlog, 2);
+	} while (res < 0 && errno == EINTR);
+	close(pmlog);
 #else							/* WIN32 */
 	/* not supported */
-	elog(FATAL, "SilentMode not supported under WIN32");
+	elog(FATAL, "silent_mode is not supported under Windows");
 #endif   /* WIN32 */
 }
 
@@ -3241,8 +3284,8 @@ BackendInitialize(Port *port)
 	if (!load_hba())
 	{
 		/*
-		 * It makes no sense continue if we fail to load the HBA file, since
-		 * there is no way to connect to the database in this case.
+		 * It makes no sense to continue if we fail to load the HBA file,
+		 * since there is no way to connect to the database in this case.
 		 */
 		ereport(FATAL,
 				(errmsg("could not load pg_hba.conf")));

src/backend/utils/misc/guc.c

@@ -10,7 +10,7 @@
  * Written by Peter Eisentraut <peter_e@gmx.net>.
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.510 2009/08/04 16:08:36 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.511 2009/08/24 20:08:32 tgl Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -734,7 +734,7 @@ static struct config_bool ConfigureNamesBool[] =
 		true, NULL, NULL
 	},
 	{
-		{"silent_mode", PGC_POSTMASTER, LOGGING_WHEN,
+		{"silent_mode", PGC_POSTMASTER, LOGGING_WHERE,
 			gettext_noop("Runs the server silently."),
 			gettext_noop("If this parameter is set, the server will automatically run in the "
 				 "background and any controlling terminals are dissociated.")

src/backend/utils/misc/postgresql.conf.sample

@@ -265,6 +265,11 @@
 #syslog_facility = 'LOCAL0'
 #syslog_ident = 'postgres'
 
+#silent_mode = off			# Run server silently.
+					# DO NOT USE without syslog or
+					# logging_collector
+					# (change requires restart)
+
 
 # - When to Log -
 
@@ -314,9 +319,6 @@
 					# statements running at least this number
 					# of milliseconds
 
-#silent_mode = off			# DO NOT USE without syslog or
-					# logging_collector
-					# (change requires restart)
 
 # - What to Log -